package com.slfx.open.api.utils;

import org.apache.commons.codec.binary.Base64;
import javax.crypto.Cipher;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;

public class RSAEncrypt {

	public static void main(String[] args) throws Exception {
		/**
		 * 随机生成的公钥为:MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCMKFPRuulH/vll0IL6NdLvHLd3gHSQJgW7uZpClLruEVqKr/YwwF+mQDgnAq1AHaP82XE4JOlKSawNTUJNxtBsu9D/mm27aXEiZprRN5fCLh5nRKDuT+SdgjFNTjdkVkRJeUp/YesaxCazMrdcFQOTYYelAjp28YyMrbzSEwl3cwIDAQAB
		 * 随机生成的私钥为: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
		 * df723820	加密后的字符串为:UJNu11tGDCPFdjg7+P+VEsCzBn0hZ/eI8IznTUMHbhmWTfpLJCgwb3Q8cWv3WvLDGfjMgH4ugM/wrCRQwlIhEmiBo+tYXo7t+njP7IvTExiOfHUXJLWm4aGPa74DED/S0O5apk1J+Kdx6eyHkc5CXKjuKLglxW05/yiUuOiJ+YM=
		 * 还原后的字符串为:df723820
		 */
		//生成公钥和私钥
		Map<Integer, String> keyMap = genKeyPair();
		//加密字符串
		String message = "df723820";
		System.out.println("随机生成的公钥为:" + keyMap.get(0));
		System.out.println("随机生成的私钥为:" + keyMap.get(1));
		String messageEn = encrypt(message,keyMap.get(0));
		System.out.println(message + "\t加密后的字符串为:" + messageEn);
		String messageDe = decrypt(messageEn,keyMap.get(1));
		System.out.println("还原后的字符串为:" + messageDe);
	}

	/** 
	 * 随机生成密钥对 
	 * @throws NoSuchAlgorithmException 
	 */  
	public static Map<Integer, String> genKeyPair() throws NoSuchAlgorithmException {
		// KeyPairGenerator类用于生成公钥和私钥对，基于RSA算法生成对象  
		KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");  
		// 初始化密钥对生成器，密钥大小为96-1024位  
		keyPairGen.initialize(1024,new SecureRandom());  
		// 生成一个密钥对，保存在keyPair中  
		KeyPair keyPair = keyPairGen.generateKeyPair();  
		RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();   // 得到私钥  
		RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();  // 得到公钥  
		String publicKeyString = new String(Base64.encodeBase64(publicKey.getEncoded()));  
		// 得到私钥字符串  
		String privateKeyString = new String(Base64.encodeBase64((privateKey.getEncoded())));  
		// 将公钥和私钥保存到Map
		Map<Integer, String> keyMap = new HashMap<Integer, String>();
		keyMap.put(0,publicKeyString);  //0表示公钥
		keyMap.put(1,privateKeyString);  //1表示私钥
		return keyMap;
	}  
	/** 
	 * RSA公钥加密 
	 *  
	 * @param str 
	 *            加密字符串
	 * @param publicKey 
	 *            公钥 
	 * @return 密文 
	 * @throws Exception 
	 *             加密过程中的异常信息 
	 */  
	public static String encrypt( String str, String publicKey ) throws Exception{
		//base64编码的公钥
		byte[] decoded = Base64.decodeBase64(publicKey);
		RSAPublicKey pubKey = (RSAPublicKey) KeyFactory.getInstance("RSA").generatePublic(new X509EncodedKeySpec(decoded));
		//RSA加密
		Cipher cipher = Cipher.getInstance("RSA");
		cipher.init(Cipher.ENCRYPT_MODE, pubKey);
		String outStr = Base64.encodeBase64String(cipher.doFinal(str.getBytes("UTF-8")));
		return outStr;
	}

	/** 
	 * RSA私钥解密
	 *  
	 * @param str 
	 *            加密字符串
	 * @param privateKey 
	 *            私钥 
	 * @return 铭文
	 * @throws Exception 
	 *             解密过程中的异常信息 
	 */  
	public static String decrypt(String str, String privateKey) throws Exception{
		//64位解码加密后的字符串
		byte[] inputByte = Base64.decodeBase64(str.getBytes("UTF-8"));
		//base64编码的私钥
		byte[] decoded = Base64.decodeBase64(privateKey);  
        RSAPrivateKey priKey = (RSAPrivateKey) KeyFactory.getInstance("RSA").generatePrivate(new PKCS8EncodedKeySpec(decoded));  
		//RSA解密
		Cipher cipher = Cipher.getInstance("RSA");
		cipher.init(Cipher.DECRYPT_MODE, priKey);
		String outStr = new String(cipher.doFinal(inputByte));
		return outStr;
	}

}

